The Severity of Environmental Contamination Caused by Saxitoxin

The Severity of Environmental Contamination Caused by Microcystins

Saxitoxin (STX) is mainly produced by dinoflagellate. It is one of the most toxic marine biological toxins known and is the main toxin of paralytic shellfish poison (PSP). When the red tide erupts, a variety of algal toxins will be produced to pollute the water environment, and STX is one of the main toxins of the red tide. When algae release STX into the water body, it accumulates in aquatic products such as filter-feeding shellfish, fish, shrimp, and crabs. And through the biological enrichment of the aquatic food chain, it is passed to the terrestrial biota, and finally to humans. Saxitoxin is distributed all over the world, especially in some countries in Europe and North America, which has seriously affected the development of local fisheries.

The Necessity of Monitoring Saxitoxin with ELISA Testing

The chemical structure of saxitoxinFig. 1 The chemical structure of saxitoxin

STX is a marine guanamine toxin, a derivative of tetrahydropurine. STX is heat-resistant, is not destroyed by human digestive enzymes, and is stable in high-temperature and acidic solutions. The toxicity of STX includes three aspects: nervous system, cardiovascular system, and cytotoxic activity. Among them, the mortality of STX is high, and there is no specific antidote. With the deterioration of the marine environment and the occurrence of a large number of red tides, countries all over the world pay more attention to the inspection of shellfish poisoning. The United States has established a shellfish poison monitoring system in 1925. Japan, Canada, etc. have similar regulations. The health warning line of STX and similar substances in drinking water is 3 μg/L. With the acquisition of anti-STX antibodies, ELISA detection technology has gradually developed. Among them, direct competition ELISA is the most commonly used method, with a detection limit of 3 pg/mL, and the detection limit of indirect ELISA can reach 10 pg/mL.


Direct 1 Step Competitive ELISA

The Advantages of ELISA Testing

  • Lower cost
  • Convenient and fast
  • High-throughput detection and analysis
  • High sensitivity and specificity

ELISA Procedure for Saxitoxin Testing

The microplates were coated with antibody which was diluted in PBS (1:2000 dilution) and incubated at 4°C overnight.
Add 50 µL PD-STX reference (0.1, 1, and 10nM) or sample solutions to microplates. [Note: Crude extract of shellfish prepared according to AOAC protocol is diluted 400 times with 0.1M sodium phosphate buffer (pH 7.4).]
Add 50 µL biotin-STX to each well, and then add 50 µL HRP-streptavidin to each well, incubated at 37°C for 30 min.
After washing three times with PBS containing 0.1% Tween 20, 100 µL of coloring reagent (OPD-H2O2) was added to each well, incubate at 37°C for 5 min.
Terminated by adding 0.2 mL of 2M HCl, the absorbance was determined at 492 nm in the Vmax automatic ELISA reader.

Creative Diagnostics has been committed to algal toxins testing by ELISA. Supported by rich professional knowledge and diversified ELISA kits products, we provide high-quality customized ELISA kits services, professional ELISA testing services, and ELISA development services related to the detection of saxitoxin. If you wish a lot of careful data, please contact us.


  1. Cusick, K.D.; Sayler, G.S. An overview on the marine neurotoxin, saxitoxin: genetics, molecular targets, methods of detection and ecological functions. Mar Drugs. 2013, 11(4): 991-1018.
  2. Wharton, R.E.; et al. Quantification of saxitoxin in human blood by ELISA. Toxicon. 2017, 133: 110-115.
  3. Sato, S.; et al. Quantitative ELISA kit for paralytic shellfish toxins coupled with sample pretreatment. J AOAC Int. 2014, 97(2): 339-344.
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